MOLECULAR DYNAMICS SIMULATIONS OF THERMAL INTERACTIONS IN NANOSCALE LIQUID CHANNELS

摘要

Molecular Dynamics (MD) simulations of nano-scale flows typically utilize fixed lattice crystal interactions between the fluid and stationary wall molecules. This approach cannot properly model thermal exchange at the wall-fluid interface. Therefore, we use an interactive thermal wall model that can properly simulate the flow and heat transfer in nano-scale channels. Using the interactive thermal wall, Fourier law of heat conduction is verified for the 3.24 nm channel, while the thermal conductivity obtained from Fourier law is verified using the predictions of Green-Kubo theory. Moreover, temperature jumps at the liquid/solid interface, corresponding to the well known Kapitza resistance, are observed. Using systematic studies thermal resistance length at the interface is characterized as a function of the surface wettability, thermal oscillation frequency, wall temperature and thermal gradient. An empirical model for the thermal resistance length, which could be used as the jump-coefficient of a Navier boundary condition, is developed.